The invention refers to a method and apparatus in an optimized system for generating long-duration rectangular current impulses, as well as high amplitude short-duration impulses, in order to test electrical equipment, to obtain high magnetic fields, and to study the material properties.
The prior art methods and equipment using a ladder network synthesis for obtaining long-duration rectangular impulses, and having as a common element solutions derived from the continued fractional development of the impedances or admittances characteristic to these circuits, are well known. Some methods and apparatus for obtaining rectangular impulses which use equal stage capacities and mutual inductances, are also known.
The disadvantage of these methods, and at the same time, of the resulting apparatus is that the values of the elements in the ladder network stages, are unequal. Such solutions are disadvantageous not only from the point of view of their practical achievement, but particularly from the point of view of the functional flexibility, that is, of the possibility to obtain different impulse shapes for a large variety of load characteristics.
There are known devices with equal stage capacities, but being designed for a certain load, they are characterized by an extremely restricted functional flexibility.
Methods and apparatus are also known, for obtaining high amplitude short-duration impulses in the presence of nonlinear loads, as it is the case with the variable resistance arresters, which use comparatively high linear resistances in order to obtain the impulse shape parameters within the necessary tolerances.
The main disadvantages lie on the one hand in their ineffeciency, and on the other, they refer to the compatibility with rectangular impulses generating equipment. Thus, an important part of the energy stored in the capacitors is uselessly consumed in the linearizing resistance, while the circuit elements, due to the required values, cannot be used for obtaining the rectangular impulses. Therefore, today, independent apparatus is used, for obtaining long-duration rectangular impulses, and high amplitude short-duration impulses, respectively.